The present invention is related generally to systems and methods for storing and displaying imagery and, in particular, to systems and methods for displaying image data remotely from a storage device when the display and the storage device are interconnected by a limited bandwidth communications medium.
Prior to the advent of digital computing, most image processing was accomplished by analog methods. For example, conventional photographs (an analog mechanism) were taken of an object or area to be studied and the photograph was physically sent to a person for analysis. If more than one person was to analyze the image date on the photograph, plural copies of the photograph had to be made or the one photograph had to be used sequentially by the various persons. Presently, much of the imagery has moved into the digital domain and images are presently either (a) taken using analog means and subsequently converted into digital data or (b) taken using digital means with direct storage onto a digital storage device. Once in digital form, an image may be readily transmitted by digital or RF means to many different users for simultaneous use.
As the precision of digital imagery has increased, the size of the digital files needed to store the images has likewise increased dramatically. It is now not unusual for a digital image (for example, an image of land from an orbiting satellite) to contain over 1 Gigabytes of data. While such a large amount of data may be preferred by an analyst, the transmission of such data over conventional data transmission systems is unwieldy and may consume a relatively large amount of the available transmission capability of a particular transmission system. For example, a typical image may contain 12,000 pixels by 8,000 pixels of data, each pixel being 8-16 bits in length for a black and white image and 24-48 bits in length for a color image. In today's communications systems, a transmission speed of 256,000 bits per second is attainable; however, even such a system would require over 51 minutes to transmit an 8 bit image and almost five hours to transmit a 16 bit color image.
The analysis of large or high resolution images, accordingly, presents considerable difficulties in the transmission of the image data from the storage medium to the display device. Note that this difficulty is present even if the storage device is physically near to the display and parallel or bus communications can be established between the storage device and the display. The difficulties are made many times more problematic when the display is physically remote from the storage device and conventional remote transmission media are used, such as a non-conditioned telephone line which may be limited in bandwidth to 30,000 bits per second or less.
To reduce the transmission problems of image data, it is known to compress the data prior to transmission and to restore the data after receipt at the display end of the transmission medium. Generally, such compression techniques rely upon the fact that there are areas in an image in which the image does not change substantially and abbreviated coding sequences can be used to transmit such non-changing areas. While some reduction in the bandwidth required to transmit compressed images is realized by such techniques, they also generally tend to filter the image and cause a loss of resolution available. While there are compression techniques which are completely reversible at the receiving end of the medium (i.e., the image received can be restored to be exactly the stored image), such techniques do not generally result in a significant bandwidth reduction (i.e., no more than 50% reduction).
Conventional compression techniques for image data are often based on mathematical relationships among the data being transmitted and may not be at all related to the types of data of interest to an analyst. Thus, often conventional compression techniques may compress out exactly the portion of an image of most interest to an analyst.
Often image analysis proceeds from a view of an overall image to identify areas of interest followed by a closed review of the identified ares of interest. Only the identified areas of interest receive close scrutiny of the analyst and the remainder of the overall image is of little or no interest. In conventional display systems which merely transmit the image from the storage device to the display, a typical user is bombarded with detail (for which he must wait for the transmission) to obtain an overall view of the image. For example, a doctor wishing to review a CAT scan of a patient would generally first view a full body image to determine the areas of possible problems. In a typical full body image, over 100 megabytes of information would have to be transmitted. Even at a transmission rate of 28.8 kilobaud, such an image would take almost an hour for transmission. Upon review of the image, the doctor may select a portion, such as a liver, for particular scrutiny. While the doctor is now able to perform such scrutiny (because the entire image has been transmitted), a considerable amount of time has elapsed and many unnecessary bytes of data were transmitted.
It is accordingly an object of the present invention to provide a novel system and method for displaying remote image data in a time and cost efficient manner.
It is a further object of the present invention to provide a novel system and method for displaying remote image data without the need to transmit an entire image while not losing resolution of areas of an image of interest.
It is another object of the present invention to provide a novel system and method for automatically selecting a portion of an image to be transmitted related to the image size on the image display device.
It is still another object of the present invention to provide a novel system and method for displaying remote image data in which the portion of the image data transmitted from remote storage device is related to a request from a user.
It is yet another object of the present invention to provide a novel system and method for displaying remote image data in which a user can selectively obtain full resolution data of a portion of an image of interest to the user.
It is still a further object of the present invention to provide a novel system and method for displaying remote image data in which the system automatically determines the need for the transmission of additional image data as the user manipulates the image data previously transmitted to him.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments.